Am 04.01.2014 17:48, schrieb clipka:
> Am 03.01.2014 16:54, schrieb Cousin Ricky:
>> clipka <ano### [at] anonymousorg> wrote:
>>> I wouldn't expect "classic" materials (i.e. defined in terms of an RGB
>>> colour) to work "out of the box" with SpectralRender. There are
>>> infinitely many spectra that match any given RGB triplet, and
>>> SpectralRender needs to resort to wild guessing in order to pick one of
>>> them.
>>
>> That's not what I'm doing.  I'm using the spectral definitions of the
>> metals
>> that are bundled with SpectralRender.  (The only RGB colors in the
>> example are
>> for the plain gray floor and walls, which I didn't see the need to
>> jump through
>> hoops just to get a flat spectral curve, and which turned out as expected
>> anyway.)
>
> I see...
>
> Looking at the M_Spectral_Metal macro, I find that it looks bogus to me.
> For starters, instead of "#if (WavelengthIndex < 0)" the tests should be
> "#if (!SpectralMode)"; the "fresnel on" should only be used in spectral
> mode (if at all); and in non-spectral mode there should only be one
> parameter to reflection, as the "metallic" keyword already takes care of
> all variable effects applicable to metals.
>
> I get good results with the following:
>
>
> #macro M_Spectral_Metal (N, K, Reflectance)
>    material {
>      texture {
>        pigment { C_Metal(N, K) }
>        finish {
>          ambient 0  emission 0  diffuse (0.5 - Reflectance*0.45)
>          reflection { Reflectance metallic }
>          conserve_energy
>          brilliance EXT_Metal(N, K)
>          metallic
>        }
>      }
>    }
> #end

Maybe this is what it was supposed to be:

#macro M_Spectral_Metal (N, K, Reflectance)
   material {
     texture {
       pigment { C_Metal(N, K) }
       finish {
         ambient 0  emission 0  diffuse (0.5 - Reflectance*0.45)
         reflection {
           #if (SpectralMode)
             Reflectance * C_Metal_(N,K), Reflectance fresnel on
           #else
             Reflectance metallic
           #end
         }
         conserve_energy
         brilliance EXT_Metal(N, K)
         metallic
       }
     }
     interior { IOR_Metal(N, K) }
   }
#end

(where C_Metal_(N,K) is identical to C_Metal(N,K) except that it omits 
the "rgb" keyword)

Post a reply to this message